Many containers, such as envelopes, re-usable envelopes, carrier envelopes, pockets, cartons, food packaging, retail packaging and forms, such as single sheet forms, folded forms, folded mailers are formed of printable sheet material that is designed to incorporate at least a partially separable portion or portions that may be used to open the container, or expose or remove an area, or separate connected portions of the form or container portions. Generally the existing tearable cut designs and tear strips are weak because of the close linear spacing of the tearable line patterns that make the tearable line weak or they have curved or L-shaped cut patterns that catch on inserting or processing equipment or when handled by a person.
Other items that have one or more layers or panels of printable sheet material are postcards, single sheet advertisements and order forms that can also incorporate at least a partially separable portion or portions. Various problems and inefficiencies are associated with the opening or separation of these portions relative to the remaining sheet material. For example, unsealing or opening of the item is often difficult, messy or damaging to the item. The existing perforation (cut and connector designs do not ensure that the desired tearing path is followed. Depending on how someone grasps and pulls the two separating portions, variable forces are applied that can subsequently cause the tearing of the two separable portions to drift away or tear into adjacent areas at each gap or connector area where the cuts are spaced apart to form gaps called connectors that are necessary to provide strength for the connection of the two separable portions for manufacture and use. Attempts at solving the problems and inefficiencies associated with manufacturing, fastening and separating such items have proven unsatisfactory.
Accordingly, there exists a need for apparatus, methods and articles of manufacture for fastening and/or separating portions of sheet material having one or more of the following attributes, capabilities or features: allows for easy release, separation or opening of connected sheet material portions; limits, minimizes or eliminates damage to the portions being separated; reduces, limits, eliminates or controls tearing of the sheet material portions during separation; reduces, limits, eliminates or controls tearing of the portions during separation regardless of the direction of separation of the connected portions; reduces, limits, eliminates or controls tearing of the portions during separation when the connected portions are separated in a particular direction; indicates tampering or attempted opening of the connected portions; prevents or reduces damage to text or graphics included on any connected/separated portions; provides an intuitive mechanism for opening or separating connected portions; makes opening containers easier; provides simple, dependable, easy-open functionality for containers; preserves the appearance and/or integrity of connected portions after separation; provides desired sturdiness of affixation/separation mechanisms; eliminates the need for equipment to open certain containers or separate connected portions; enables re-use, resealing or remailing of sheet material and containers made from sheet material; prevents accidental opening of perforations on containers; allows for easy connection of container portions; removes or reduces uncertainty in determining the quantity and extent of affixation material to include on the portions to be connected; enables the manufacture, sealing and use of containers with less affixation material; simplifies the manufacturing process of containers and other sheet material items; removes or reduces potential difficulties in processing and/or handling sheet material items; and allows for easy use of sheet material item manufacturing and handling equipment, such as high-speed envelope printing and converting technology, envelope insertion and sealing equipment, and mail processing technologies.